| 摘要 |
1499034 Wellbore fluids CHEMICAL ADDITIVES CO 5 April 1975 14033/75 Heading E1F [Also in Division C3] An aqueous clay-free wellbore fluid comprises at least 1% of a brine forming soluble salt or mixtures of salts, and a starch ether, a starch ester or a mixture thereof for fluid loss control. The starch derivative is present in an amount of from 0.15-30.0 g/l. The starch ether is preferably cationic and contains -nitrogen or has the formula: starch - O - CR 1 R 2 R 3 where R 1 =OH, CH 2 OH or H, R 2 =H or hydrocarbyl, R 3 =hydrocarbyl H, COOH, CHR 4 OH, or NR 5 R 6 , R 4 = hydrocarbyl and R 5 and R 6 =H or hydrocarbyl. The wellbore fluid may contain hydroxyethyl cellulose as a viscosifier.
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